1. Field of the Invention
The present invention relates to image capturing method and image capturing apparatus that compensates for distortions from such causes as camera-shake in an image captured by an image capturing device equipped with a CMOS type image capturing module, and creates a high quality distortion-compensated image.
2. Description of the Related Art
In recent years, image capturing module based on CMOS (Complementary Metal Oxide Semiconductor) sensors, which is smaller and requires less power compared to CCD (Charge Coupled Device), have been utilized in image capturing devices such as mobile phones and digital cameras.
However, in a CMOS sensor image capturing module the focal plane electronic shutter system, which exposes and scans individual pixels and accumulated charges are output sequentially, is often used instead of the global electronic shutter system such as a CCD which simultaneously transfers every pixel charge accumulated for an entire image when an electronic shutter has been operated.
Therefore, in a CMOS sensor, the timing of the output signal becomes delayed depending on the output electrical charge, which can cause an image to be distorted in the direction of the scan if camera-shake occurs during scanning.
For existing technologies that compensate this image distortion, Patent Documents 1 and 2 propose technologies that utilize gyro sensors to detect camera-shake and compensate captured images. Also, Patent Document 3 proposes circuitry design that allow full screen simultaneous image capturing on a CMOS sensor. However, these technologies require additional circuitry which is costly.
Also, Patent Documents 4 through 6 propose technologies that compensate for distortions in images captured using focal plane electronic shutter system with software processing where the correlation with the previous frame or adjoining horizontal groups is computed, or interpolation is performed based on the preceding and succeeding frames. However, these methods require heavy CPU load, and they have limited accuracy in their compensation when a captured image is blurred at the time of it being captured.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-235819
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-074678
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2007-142587
Patent Document 4: Japanese Unexamined Patent Application Publication No. 2007-208580
Patent Document 5: Japanese Unexamined Patent Application Publication No. 2006-148496
Patent Document 6: Japanese Unexamined Patent Application Publication No. 2004-363869